It is important in producing displays or prints from digital images to fit the dynamic range of the originally captured scene to the dynamic range of the materials available for displaying or printing using the best possible transform. Digital images are usually captured in linear form. A limiting factor is the dynamic range of the materials available for displaying or printing. By selectively choosing the proper transform for displaying or printing, it is possible to display or print esthetically pleasing images on materials that have less dynamic range than the original scene.
As new materials such as thermal print media and receivers and ink jet technologies have become available for displaying or printing, they have introduced larger dynamic range than available with previous technologies. It is well known how to display or print digital images on these types of media. However, it is difficult to design different transforms that best take advantage of these new media. A key element in any new transform is to be able to utilize the full dynamic range of the media for displaying or printing the digital images.
There have been a number of techniques for improving the tone reproduction of digital images, see for example, U.S. Pat. Nos. 4,792,518 and 5,300,381. For a discussion of tone reproduction, see "The Tone Reproduction of Colour Photographic Materials," R. W. G. Hunt, I. T. Pitt, and P. C. Ward, J. Photog. Sci., 17:198(1969).
As set forth in the above disclosures, a number of techniques are disclosed which require that the media be photographic media and the techniques for making the images are very complex. The publication by Hunt et al describes the "ideal system" for printing photographic images to correct for camera flare, printer flare, and viewing flare but offers no practical way to implement this theoretical tone reproduction curve.
U.S. Pat. No. 5,528,339 discloses techniques for improving the tone reproduction of digital images on other media such as thermal, ink jet and electrophotographic. However, the media available for the printing of the digital images far exceeds the dynamic range previously described by having lower minimum densities and considerably higher maximum densities. The same problems exist for soft copy outputs on screens.
Heretofore, the printing of digital images from digital capture sources is accomplished by calibrating the computer monitor used to view the image so that it visually gives a preview of what the print will look like when it is printed so that "what you see is what you get." References which discuss the strategy for printing digital images include The User's Guide for Adobe Photoshop 4.0 (1996); "Preparing Digital Images for Print", by Sybil Ihrig and Emil Ihring, published by McGraw Hill, N.Y. (1996); "Photoshop Artistry", by Barry Haynes and Wendy Crumpler, published by Sybex, San Francisco, Calif. (1995); and "Macworld Photoshop 3 Bible 2nd Edition", by Deke McClelland, published by IDG Books, Foster City, Calif. (1994).
The digital image when displayed in linear form does not look good on the monitor and is difficult to judge for image quality.
The big disadvantage of displaying the digital data in a form optimized for viewing first is that the exposure latitude of picture taking is severely comprised as important detail information for printing is discarded to shape the data for display on the monitor screen.